Many operators provide media as well as high speed interne access, video on demand (VOD), Voice over IP (VoIP) telephone, and numerous other services to end-users. To provide such services, system operators must manage and maintain increasingly complex networks. FIG. 1 depicts a block diagram showing an example of such a network. A national or general processing center 101 (e.g., a central office or headend) may include elements such as VOD servers, servers for receiving and encapsulating programming content, management servers, and the like. Processing center 101 communicates with multiple regional processing centers 103 over a backbone network 105, with regional processing centers 103 also including facilities for VOD and programming reception/encapsulation. Each regional processing center 103 communicates over a regional access network 107 with multiple hubs 109. Each hub 109 includes a termination system, devices for quadrature amplitude modulation/demodulation (QAM), and other elements for transmission and reception of information.
From hubs 109, individual homes or other end-user locations are reached via an end-user distribution network 111, which may comprise, for example, an optical fiber, wireless, or a hybrid fiber coaxial cable (HFC) access network. A fiber optic portion 113 of end-user distribution network 111 may include multiple nodes 117. A transmission line portion 115 of end-user distribution network 111 may include feeder lines 119 extending from nodes 117. Drop end-user lines 121 typically extend from taps in feeder lines 119 and connect to the end-user premises. Amplifiers are often distributed along the feeder lines. Alternating current (AC) power may also be input into the feeder cables so as to provide a power source for the amplifiers. For simplicity, FIG. 1 only shows a very small part of transmission line portion 115 of an end-user distribution network associated with a single node. Typically, distribution plants 123 associated with hubs may be the largest part of the system, and there may be many end-users receiving service through a particular hub.
Communication through a transmission line may be affected in many ways. For example, temperature changes can affect signal quality in transmission lines. To detect, prevent and correct communication problems, signal quality measurements from the transmission line part of an end-user distribution network can be very useful in assessing transmission quality. In addition, a media distribution operator may need to verify that specific media content is delivered to end users in accordance with schedule information, for example, in order to meet contractual obligations.